Firefox with the add-ons Ad Block Plus and (only on Firefox) NoScript (drag a Temp allow all button to the toolbar) and also HTTPSEverywhere (encrypts your web traffic if possible)
You'll have to tweak Ad Block Plus preferences to block all ads
This is why one drags a NoScript "Temp all all" button to the Firefox toolbar, so it's easy and fast to click to allow scripts to run on new sites.
NoScript is the best web browser protection possible, it's saved me from two OS X trojans already.
2.2 million users of NoScript
14.4 million users of Ad Block Plus
HTTPS Everywhere, from the people trying to protect your privacy etc., rights online
And if your really computer savvy, then you can install a hosts file addition blocks a lot of other garbage like ad trackers etc.